It is common to utilize ozone for removing materials from over semiconductor substrates during semiconductor device fabrication. For instance, ozone can be utilized for removing photoresist and other organic materials. The ozone is typically generated proximate to, or within, a reaction chamber. The semiconductor substrate is provided within the reaction chamber, and the ozone is contacted with the material which is to be removed.
Ozone can be utilized for removing organic materials, such as, for example, photoresist, in that the ozone can oxidize the organic material and thereby convert the organic material to a form which is more readily removed from over a semiconductor substrate than was the organic material prior to oxidation.
A method of forming ozone is to feed a diatomic oxygen (O2) containing feed gas into an ozone generator. The feed gas is generally about 99.9% O2 (by volume), with the remaining 0.1% of the feed gas comprising mostly nitrogen (N2). Occasionally, additional nitrogen may be spiked into the feed gas to raise a concentration of nitrogen up to about 5%. A reason for utilizing the relatively low purity oxygen as a feed gas for generating ozone is that it can be cheaper than higher purity oxygen. Another reason is that there can be a reduced risk of flame or explosion in utilizing a lower purity oxygen, relative to that which would exist in utilizing a higher purity oxygen.
The invention encompasses new methods of forming and utilizing ozone in removing materials from over semiconductor substrates.